draft-ietf-uta-xmpp-07.txt   rfc7590.txt 
Network Working Group P. Saint-Andre Internet Engineering Task Force (IETF) P. Saint-Andre
Internet-Draft &yet Request for Comments: 7590 &yet
Updates: 6120 (if approved) T. Alkemade Updates: 6120 T. Alkemade
Intended status: Standards Track Category: Standards Track June 2015
Expires: October 25, 2015 April 23, 2015 ISSN: 2070-1721
Use of Transport Layer Security (TLS) in the Extensible Messaging and Use of Transport Layer Security (TLS) in the
Presence Protocol (XMPP) Extensible Messaging and Presence Protocol (XMPP)
draft-ietf-uta-xmpp-07
Abstract Abstract
This document provides recommendations for the use of Transport Layer This document provides recommendations for the use of Transport Layer
Security (TLS) in the Extensible Messaging and Presence Protocol Security (TLS) in the Extensible Messaging and Presence Protocol
(XMPP). This document updates RFC 6120. (XMPP). This document updates RFC 6120.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on October 25, 2015. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7590.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 16 skipping to change at page 2, line 16
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3 3. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Support for TLS . . . . . . . . . . . . . . . . . . . . . 3 3.1. Support for TLS . . . . . . . . . . . . . . . . . . . . . 3
3.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Compression . . . . . . . . . . . . . . . . . . . . . . . 3
3.3. Session Resumption . . . . . . . . . . . . . . . . . . . 3 3.3. Session Resumption . . . . . . . . . . . . . . . . . . . 3
3.4. Authenticated Connections . . . . . . . . . . . . . . . . 4 3.4. Authenticated Connections . . . . . . . . . . . . . . . . 4
3.5. Server Name Indication . . . . . . . . . . . . . . . . . 5 3.5. Server Name Indication . . . . . . . . . . . . . . . . . 5
3.6. Human Factors . . . . . . . . . . . . . . . . . . . . . . 5 3.6. Human Factors . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6 5.2. Informative References . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . 7 Appendix A. Implementation Notes . . . . . . . . . . . . . . . . 9
Appendix A. Implementation Notes . . . . . . . . . . . . . . . . 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The Extensible Messaging and Presence Protocol (XMPP) [RFC6120] The Extensible Messaging and Presence Protocol (XMPP) [RFC6120]
(along with its precursor, the so-called "Jabber protocol") has used (along with its precursor, the so-called "Jabber protocol") has used
Transport Layer Security (TLS) [RFC5246] (along with its precursor, Transport Layer Security (TLS) [RFC5246] (along with its precursor,
Secure Sockets Layer or SSL) since 1999. Both [RFC6120] and its Secure Sockets Layer or SSL) since 1999. Both [RFC6120] and its
predecessor [RFC3920] provided recommendations regarding the use of predecessor [RFC3920] provided recommendations regarding the use of
TLS in XMPP. In order to address the evolving threat model on the TLS in XMPP. In order to address the evolving threat model on the
Internet today, this document provides stronger recommendations. Internet today, this document provides stronger recommendations.
In particular, this document updates [RFC6120] by specifying that In particular, this document updates [RFC6120] by specifying that
XMPP implementations and deployments MUST follow the best current XMPP implementations and deployments MUST follow the best current
practices documented in the "Recommendations for Secure Use of TLS practices documented in the "Recommendations for Secure Use of TLS
and DTLS" [I-D.ietf-uta-tls-bcp]. This includes stronger and DTLS" [RFC7525]. This includes stronger recommendations
recommendations regarding SSL/TLS protocol versions, fallback to regarding SSL/TLS protocol versions, fallback to lower versions,
lower versions, TLS-layer compression, TLS session resumption, cipher TLS-layer compression, TLS session resumption, cipher suites, public
suites, public key lengths, forward secrecy, and other aspects of key lengths, forward secrecy, and other aspects of using TLS with
using TLS with XMPP. XMPP.
2. Terminology 2. Terminology
Various security-related terms are to be understood in the sense Various security-related terms are to be understood in the sense
defined in [RFC4949]. defined in [RFC4949].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
3. Recommendations 3. Recommendations
The best current practices documented in the "Recommendations for The best current practices documented in the "Recommendations for
Secure Use of TLS and DTLS" [I-D.ietf-uta-tls-bcp] are included here Secure Use of TLS and DTLS" [RFC7525] are included here by reference.
by reference. Instead of repeating those recommendations here, this Instead of repeating those recommendations here, this document mostly
document mostly provides supplementary information regarding secure provides supplementary information regarding secure implementation
implementation and deployment of XMPP technologies. and deployment of XMPP technologies.
3.1. Support for TLS 3.1. Support for TLS
Support for TLS (specifically, the XMPP profile of STARTTLS) is Support for TLS (specifically, the XMPP profile of STARTTLS) is
mandatory for XMPP implementations, as already specified in [RFC6120] mandatory for XMPP implementations, as already specified in [RFC6120]
and its predecessor [RFC3920]. and its predecessor [RFC3920].
The server (i.e., the XMPP receiving entity) to which a client or The server (i.e., the XMPP receiving entity) to which a client or
peer server (i.e., the XMPP initiating entity) connects might not peer server (i.e., the XMPP initiating entity) connects might not
offer a stream feature of <starttls xmlns='urn:ietf:params:xml:ns offer a stream feature of <starttls xmlns='urn:ietf:params:xml:ns
:xmpp-tls'/>. Although in general this stream feature indicates that :xmpp-tls'/>. Although in general this stream feature indicates that
the server supports XMPP 1.0 and therefore supports TLS, that this the server supports and offers TLS, this stream feature might be
stream feature might be stripped out by an attacker (see Section 2.1 stripped out by an attacker (see Section 2.1 of [RFC7457]).
of [RFC7457]). Similarly, the <required/> child element of the Similarly, the <required/> child element of the <starttls/> stream
<starttls/> stream feature is used to indicate that negotiation of feature is used to indicate that negotiation of TLS is mandatory;
TLS is mandatory, but could also be stripped out by an attacker. however, this could also be stripped out by an attacker. Therefore,
Therefore, the initiating entity MUST NOT be deterred from attempting the initiating entity MUST NOT be deterred from attempting TLS
TLS negotiation even if the receiving entity does not advertise negotiation even if the receiving entity does not advertise support
support for TLS. Instead, the initiating entity SHOULD (based on for TLS. Instead, the initiating entity SHOULD (based on local
local policy) proceed with the stream negotiation and attempt to policy) proceed with the stream negotiation and attempt to negotiate
negotiate TLS. TLS.
3.2. Compression 3.2. Compression
XMPP supports an application-layer compression technology [XEP-0138]. XMPP supports an application-layer compression technology [XEP-0138].
Although this XMPP extension might have slightly stronger security Although this XMPP extension might have slightly stronger security
properties than TLS-layer compression (since it is enabled after SASL properties than TLS-layer compression (since it is enabled after
authentication, as described in [XEP-0170]), this document neither Simple Authentication and Security Layer (SASL) authentication, as
encourages nor discourages use of XMPP-layer compression. described in [XEP-0170]), this document neither encourages nor
discourages use of XMPP-layer compression.
3.3. Session Resumption 3.3. Session Resumption
To improve the reliability of communications over XMPP, it is common To improve the reliability of communications over XMPP, it is common
practice for clients and servers to implement the stream management practice for clients and servers to implement the stream management
extension [XEP-0198]. Although that specification includes a method extension [XEP-0198]. Although that specification includes a method
for resumption of XMPP streams at the application layer, also using for resumption of XMPP streams at the application layer, also using
session resumption at the TLS layer further optimizes the overall session resumption at the TLS layer further optimizes the overall
process of resuming an XMPP session (see [XEP-0198] for detailed process of resuming an XMPP session (see [XEP-0198] for detailed
information). Whether or not XEP-0198 is used for application-layer information). Whether or not XEP-0198 is used for application-layer
session resumption, implementations MUST follow the recommendations session resumption, implementations MUST follow the recommendations
provided in [I-D.ietf-uta-tls-bcp] regarding TLS-layer session provided in [RFC7525] regarding TLS-layer session resumption.
resumption.
3.4. Authenticated Connections 3.4. Authenticated Connections
Both the core XMPP specification [RFC6120] and the "CertID" Both the core XMPP specification [RFC6120] and the CertID
specification [RFC6125] provide recommendations and requirements for specification [RFC6125] provide recommendations and requirements for
certificate validation in the context of authenticated connections. certificate validation in the context of authenticated connections.
This document does not supersede those specifications (e.g., it does This document does not supersede those specifications (e.g., it does
not modify the recommendations in [RFC6120] regarding the Subject not modify the recommendations in [RFC6120] regarding the Subject
Alternative Names or other certificate details that need to be Alternative Names or other certificate details that need to be
supported for authentication of XMPP connections using PKIX supported for authentication of XMPP connections using PKIX
certificates). certificates).
Wherever possible, it is best to prefer authenticated connections Wherever possible, it is best to prefer authenticated connections
(along with SASL [RFC4422]), as already stated in the core XMPP (along with SASL [RFC4422]), as already stated in the core XMPP
skipping to change at page 4, line 32 skipping to change at page 4, line 32
o Clients MUST authenticate servers. o Clients MUST authenticate servers.
o Servers MUST authenticate clients. o Servers MUST authenticate clients.
o Servers SHOULD authenticate other servers. o Servers SHOULD authenticate other servers.
This document does not mandate that servers need to authenticate peer This document does not mandate that servers need to authenticate peer
servers, although such authentication is strongly preferred. servers, although such authentication is strongly preferred.
Unfortunately, in multi-tenanted environments it can be extremely Unfortunately, in multi-tenanted environments it can be extremely
difficult to obtain and deploy PKIX certificates with the proper difficult to obtain and deploy PKIX certificates with the proper
Subject Alternative Names (see [I-D.ietf-xmpp-dna] and Subject Alternative Names (see [XMPP-DNA] and [PKIX-POSH] for
[I-D.ietf-xmpp-posh] for details). To overcome that difficulty, the details). To overcome that difficulty, the Domain Name Associations
Domain Name Associations (DNA) specification [I-D.ietf-xmpp-dna] (DNAs) specification [XMPP-DNA] describes a framework for XMPP server
describes a framework for XMPP server authentication methods, which authentication methods, which include not only PKIX but also DNS-
include not only PKIX but also DNS-Based Authentication of Named Based Authentication of Named Entities (DANE) as defined in
Entities (DANE) as defined in [I-D.ietf-dane-srv] and PKIX over [DANE-SRV] and PKIX over Secure HTTP (POSH) as defined in
Secure HTTP (POSH) as defined in [I-D.ietf-xmpp-posh]. These methods [PKIX-POSH]. These methods can provide a basis for server identity
can provide a basis for server identity verification when appropriate verification when appropriate PKIX certificates cannot be obtained
PKIX certificates cannot be obtained and deployed. and deployed.
Given the pervasiveness of eavesdropping [RFC7258], even an encrypted Given the pervasiveness of eavesdropping [RFC7258], even an encrypted
but unauthenticated connection might be better than an unencrypted but unauthenticated connection might be better than an unencrypted
connection in these scenarios (this is similar to the "better than connection in these scenarios (this is similar to the "better-than-
nothing security" approach for IPsec [RFC5386]). Encrypted but nothing security" approach for IPsec [RFC5386]). Encrypted but
unauthenticated connections include connections negotiated using unauthenticated connections include connections negotiated using
anonymous Diffie-Hellman mechanisms or using self-signed anonymous Diffie-Hellman mechanisms or using self-signed
certificates, among others. In particular for XMPP server-to-server certificates, among others. In particular for XMPP server-to-server
interactions, it can be reasonable for XMPP server implementations to interactions, it can be reasonable for XMPP server implementations to
accept encrypted but unauthenticated connections when Server Dialback accept encrypted but unauthenticated connections when Server Dialback
keys [XEP-0220] are used; such keys on their own provide only weak keys [XEP-0220] are used; such keys on their own provide only weak
identity verification (made stronger through the use of DNSSEC identity verification (made stronger through the use of DNSSEC
[RFC4033]), but this at least enables encryption of server-to-server [RFC4033]), but this at least enables encryption of server-to-server
connections. The DNA prooftypes described above are intended to connections. The DNA prooftypes mentioned above are intended to
mitigate the residual need for encrypted but unauthenticated mitigate the residual need for encrypted but unauthenticated
connections in these scenarios. connections in these scenarios.
3.5. Server Name Indication 3.5. Server Name Indication
Although there is no harm in supporting the TLS Server Name Although there is no harm in supporting the TLS Server Name
Indication (SNI) extension [RFC6066], this is not necessary since the Indication (SNI) extension [RFC6066], this is not necessary since the
same function is served in XMPP by the 'to' address of the initial same function is served in XMPP by the 'to' address of the initial
stream header as explained in Section 4.7.2 of [RFC6120]. stream header as explained in Section 4.7.2 of [RFC6120].
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o If authenticated encryption is used, determine how the connection o If authenticated encryption is used, determine how the connection
was authenticated or verified (e.g., via PKI, DANE, POSH, or was authenticated or verified (e.g., via PKI, DANE, POSH, or
Server Dialback). Server Dialback).
o Inspect the certificate offered by an XMPP server. o Inspect the certificate offered by an XMPP server.
o Determine the cipher suite used to encrypt a connection. o Determine the cipher suite used to encrypt a connection.
o Be warned if the certificate changes for a given server. o Be warned if the certificate changes for a given server.
4. IANA Considerations 4. Security Considerations
This document requests no actions of the IANA.
5. Security Considerations
The use of TLS can help limit the information available for The use of TLS can help to limit the information available for
correlation between the XMPP application layer and the underlying correlation between the XMPP application layer and the underlying
network and transport layers. As typically deployed, XMPP network and transport layers. As typically deployed, XMPP
technologies do not leave application-layer routing data (such as technologies do not leave application-layer routing data (such as
XMPP 'to' and 'from' addresses) at rest on intermediate systems, XMPP 'to' and 'from' addresses) at rest on intermediate systems,
since there is only one hop between any two given XMPP servers. As a since there is only one hop between any two given XMPP servers. As a
result, encrypting all hops (sender's client to sender's server, result, encrypting all hops (sender's client to sender's server,
sender's server to recipient's server, recipient's server to sender's server to recipient's server, and recipient's server to
recipient's client) can help to limit the amount of "metadata" that recipient's client) can help to limit the amount of metadata that
might leak. might leak.
It is possible that XMPP servers themselves might be compromised. In It is possible that XMPP servers themselves might be compromised. In
that case, per-hop encryption would not protect XMPP communications, that case, per-hop encryption would not protect XMPP communications,
and even end-to-end encryption of (parts of) XMPP stanza payloads and even end-to-end encryption of (parts of) XMPP stanza payloads
would leave addressing information and XMPP roster data in the clear. would leave addressing information and XMPP roster data in the clear.
By the same token, it is possible that XMPP clients (or the end-user By the same token, it is possible that XMPP clients (or the end-user
devices on which such clients are installed) could also be devices on which such clients are installed) could also be
compromised, leaving users utterly at the mercy of an adversary. compromised, leaving users utterly at the mercy of an adversary.
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XMPP network are based on the assumption that XMPP servers and XMPP network are based on the assumption that XMPP servers and
clients have not been subject to widespread compromise. If this clients have not been subject to widespread compromise. If this
assumption is valid, then ubiquitous use of per-hop TLS channel assumption is valid, then ubiquitous use of per-hop TLS channel
encryption and more significant deployment of end-to-end object encryption and more significant deployment of end-to-end object
encryption technologies will serve to protect XMPP communications to encryption technologies will serve to protect XMPP communications to
a measurable degree, compared to the alternatives. a measurable degree, compared to the alternatives.
This document covers only communication over the XMPP network and This document covers only communication over the XMPP network and
does not take into account gateways to non-XMPP networks. As an does not take into account gateways to non-XMPP networks. As an
example, for security considerations related to gateways between XMPP example, for security considerations related to gateways between XMPP
and the Session Initiation Protocol (SIP) see [RFC7247] and and the Session Initiation Protocol (SIP), see [RFC7247] and
[I-D.ietf-stox-im]. [RFC7572].
6. References 5. References
6.1. Normative References 5.1. Normative References
[I-D.ietf-uta-tls-bcp] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Sheffer, Y., Holz, R., and P. Saint-Andre, Requirement Levels", BCP 14, RFC 2119,
"Recommendations for Secure Use of TLS and DTLS", draft- DOI 10.17487/RFC2119, March 1997,
ietf-uta-tls-bcp-11 (work in progress), February 2015. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
Requirement Levels", BCP 14, RFC 2119, March 1997. FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<http://www.rfc-editor.org/info/rfc4949>.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2", RFC [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
4949, August 2007. (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
(TLS) Protocol Version 1.2", RFC 5246, August 2008. Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
March 2011, <http://www.rfc-editor.org/info/rfc6120>.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Protocol (XMPP): Core", RFC 6120, March 2011. Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <http://www.rfc-editor.org/info/rfc6125>.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
Verification of Domain-Based Application Service Identity "Recommendations for Secure Use of Transport Layer
within Internet Public Key Infrastructure Using X.509 Security (TLS) and Datagram Transport Layer Security
(PKIX) Certificates in the Context of Transport Layer (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
Security (TLS)", RFC 6125, March 2011. 2015, <http://www.rfc-editor.org/info/rfc7525>.
6.2. Informative References 5.2. Informative References
[I-D.ietf-dane-srv] [DANE-SRV] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS-
Finch, T., Miller, M., and P. Saint-Andre, "Using DNS- Based Authentication of Named Entities (DANE) TLSA
Based Authentication of Named Entities (DANE) TLSA records records with SRV and MX records.", Work in Progress,
with SRV and MX records.", draft-ietf-dane-srv-13 (work in draft-ietf-dane-srv-14, April 2015.
progress), April 2015.
[I-D.ietf-stox-im] [PKIX-POSH] Miller, M. and P. Saint-Andre, "PKIX over Secure HTTP
Saint-Andre, P., Houri, A., and J. Hildebrand, (POSH)", Work in Progress, draft-ietf-xmpp-posh-04,
"Interworking between the Session Initiation Protocol February 2015.
(SIP) and the Extensible Messaging and Presence Protocol
(XMPP): Instant Messaging", draft-ietf-stox-im-13 (work in
progress), March 2015.
[I-D.ietf-xmpp-dna] [RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Saint-Andre, P. and M. Miller, "Domain Name Associations Protocol (XMPP): Core", RFC 3920, DOI 10.17487/RFC3920,
(DNA) in the Extensible Messaging and Presence Protocol October 2004, <http://www.rfc-editor.org/info/rfc3920>.
(XMPP)", draft-ietf-xmpp-dna-10 (work in progress), March
2015.
[I-D.ietf-xmpp-posh] [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Miller, M. and P. Saint-Andre, "PKIX over Secure HTTP Rose, "DNS Security Introduction and Requirements",
(POSH)", draft-ietf-xmpp-posh-04 (work in progress), RFC 4033, DOI 10.17487/RFC4033, March 2005,
February 2015. <http://www.rfc-editor.org/info/rfc4033>.
[RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence [RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
Protocol (XMPP): Core", RFC 3920, October 2004. Authentication and Security Layer (SASL)", RFC 4422,
DOI 10.17487/RFC4422, June 2006,
<http://www.rfc-editor.org/info/rfc4422>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC5386] Williams, N. and M. Richardson, "Better-Than-Nothing
Rose, "DNS Security Introduction and Requirements", RFC Security: An Unauthenticated Mode of IPsec", RFC 5386,
4033, March 2005. DOI 10.17487/RFC5386, November 2008,
<http://www.rfc-editor.org/info/rfc5386>.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Security Layer (SASL)", RFC 4422, June 2006. Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011,
<http://www.rfc-editor.org/info/rfc6066>.
[RFC5386] Williams, N. and M. Richardson, "Better-Than-Nothing [RFC7247] Saint-Andre, P., Houri, A., and J. Hildebrand,
Security: An Unauthenticated Mode of IPsec", RFC 5386, "Interworking between the Session Initiation Protocol
November 2008. (SIP) and the Extensible Messaging and Presence Protocol
(XMPP): Architecture, Addresses, and Error Handling",
RFC 7247, DOI 10.17487/RFC7247, May 2014,
<http://www.rfc-editor.org/info/rfc7247>.
[RFC6066] Eastlake, D., "Transport Layer Security (TLS) Extensions: [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is
Extension Definitions", RFC 6066, January 2011. an Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <http://www.rfc-editor.org/info/rfc7258>.
[RFC7247] Saint-Andre, P., Houri, A., and J. Hildebrand, [RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
"Interworking between the Session Initiation Protocol Known Attacks on Transport Layer Security (TLS) and
(SIP) and the Extensible Messaging and Presence Protocol Datagram TLS (DTLS)", RFC 7457, DOI 10.17487/RFC7457,
(XMPP): Architecture, Addresses, and Error Handling", RFC February 2015, <http://www.rfc-editor.org/info/rfc7457>.
7247, May 2014.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an [RFC7572] Saint-Andre, P., Houri, A., and J. Hildebrand,
Attack", BCP 188, RFC 7258, May 2014. "Interworking between the Session Initiation Protocol
(SIP) and the Extensible Messaging and Presence Protocol
(XMPP): Instant Messaging", RFC 7572,
DOI 10.17487/RFC7572, June 2015,
<http://www.rfc-editor.org/info/rfc7572>.
[RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing [XEP-0138] Hildebrand, J. and P. Saint-Andre, "Stream Compression",
Known Attacks on Transport Layer Security (TLS) and XSF XEP 0138, May 2009,
Datagram TLS (DTLS)", RFC 7457, February 2015. <http://xmpp.org/extensions/xep-0138.html>.
[XEP-0138] [XEP-0170] Saint-Andre, P., "Recommended Order of Stream Feature
Hildebrand, J. and P. Saint-Andre, "Stream Compression", Negotiation", XSF XEP 0170, January 2007,
XSF XEP 0138, May 2009. <http://xmpp.org/extensions/xep-0170.html>.
[XEP-0170] [XEP-0198] Karneges, J., Saint-Andre, P., Hildebrand, J., Forno, F.,
Saint-Andre, P., "Recommended Order of Stream Feature Cridland, D., and M. Wild, "Stream Management", XSF XEP
Negotiation", XSF XEP 0170, January 2007. 0198, June 2011,
<http://xmpp.org/extensions/xep-0198.html>.
[XEP-0198] [XEP-0220] Miller, J., Saint-Andre, P., and P. Hancke, "Server
Karneges, J., Saint-Andre, P., Hildebrand, J., Forno, F., Dialback", XSF XEP 0220, August 2014,
Cridland, D., and M. Wild, "Stream Management", XSF XEP <http://xmpp.org/extensions/xep-0220.html>.
0198, June 2011.
[XEP-0220] [XMPP-DNA] Saint-Andre, P. and M. Miller, "Domain Name Associations
Miller, J., Saint-Andre, P., and P. Hancke, "Server (DNA) in the Extensible Messaging and Presence Protocol
Dialback", XSF XEP 0220, September 2013. (XMPP)", Work in Progress, draft-ietf-xmpp-dna-10, March
2015.
Appendix A. Implementation Notes Appendix A. Implementation Notes
Some governments enforce legislation prohibiting the export of strong Some governments enforce legislation prohibiting the export of strong
cryptographic technologies. Nothing in this document ought to be cryptographic technologies. Nothing in this document ought to be
taken as advice to violate such prohibitions. taken as advice to violate such prohibitions.
Appendix B. Acknowledgements Acknowledgements
The authors would like to thank the following individuals for their The authors would like to thank the following individuals for their
input: Dave Cridland, Philipp Hancke, Olle Johansson, Steve Kille, input: Dave Cridland, Philipp Hancke, Olle Johansson, Steve Kille,
Tobias Markmann, Matt Miller, and Rene Treffer. Tobias Markmann, Matt Miller, and Rene Treffer.
Roni Even caught several important issues in his review on behalf of Roni Even caught several important issues in his review on behalf of
the General Area Review Team. the General Area Review Team.
Ben Campbell, Spencer Dawkins, and Barry Leiba provided helpful input Ben Campbell, Spencer Dawkins, and Barry Leiba provided helpful input
during IESG review. during IESG review.
Thanks to Leif Johansson and Orit Levin as chairs of the UTA WG, Ben Thanks to Leif Johansson and Orit Levin as chairs of the UTA WG, Ben
Campbell and Joe Hildebrand as chairs of the XMPP WG, and Stephen Campbell and Joe Hildebrand as chairs of the XMPP WG, and Stephen
Farrell as the sponsoring Area Director. Farrell as the sponsoring Area Director.
Authors' Addresses Authors' Addresses
Peter Saint-Andre Peter Saint-Andre
&yet &yet
Email: peter@andyet.com EMail: peter@andyet.com
URI: https://andyet.com/ URI: https://andyet.com/
Thijs Alkemade Thijs Alkemade
Email: me@thijsalkema.de EMail: me@thijsalkema.de
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